This is a tool I created intended to be used in forensics challenges for CTFs where you are given a corrupted PNG file. After using a tool such as pngcheck, if there are critical chunks with incorrect sizes defined, then this tool will automatically go through each critical chunk and fix their sizes for you.
Note that this tool assumes that it is only the chunksizes that are incorrect. If the CRCs are incorrect as well, then you will have to manually go through the output file and calculate the CRCs yourself and replace them in the file.
To use the tool, simply do the following:
git clone https://github.com/farazsth98/ctf-png-chunksize-fixer.git
cd ctf-png-chunksize-fixer
chmod +x ./png-chunksize-fixer.py
./png-chunksize-fixer -i input_file.png -o output_file.pngThis project is licensed under the MIT License - see the LICENSE.md file for details